Work on Muni Metro train service may make the traffic situation even worse.

For the next six months, Muni Metro, under the city, will not be a travel option past 10 p.m.

"I work at the Ferry Building and a lot of people get out past 9 o'clock at night. So it's going to be unfortunate for them. I don't know how they're going to find a way to get home unless they navigate the bus system," San Francisco resident Jenoah Timko said.

For the rest of the weekend, BART trains will not run through the Transbay Tube.

Workers have already started setting up signs to direct passengers to the temporary bus bridge but the CHP recommends people just avoid a cross-bay weekend trip if possible.

"BART's advising the bus bridge is a lifeline service only. So don't depend on that for your trip to San Francisco. It will delay your trip by an average of one to two hours extra, what it usually takes through the Transbay," CHP's Daniel Hill said.

That may not be an option for weekend workers. For some Bay Area visitors, the shutdown was a surprise.

Ehsen Tayyabi is visiting from Toronto and staying in San Francisco, but he wanted to go to an A's game this weekend with his friends.

"Apparently, it's under construction for the next two days, so we'll be having to take an Uber or something or a cab, so that's one big headache," he said.

To make sure passengers are able to navigate their way through downtown San Francisco between the bus bridge and subway trains, BART has dispatched a small army of street guides to help direct passengers to the drop off and loading points for the shuttle buses.

The Transbay tube will be shut down until Monday morning so crews can replace transfer rails near West Oakland BART Station.